<template>
  <div class="score-case">
    <div class="table">
      <table>
        <thead>
          <tr>
            <th>编号</th>
            <th>科目</th>
            <th>成绩</th>
            <th>考试时间</th>
            <th>操作</th>
          </tr>
        </thead>
        <tbody>
          <!-- v-for循环渲染数组 -->
          <tr v-for="(item, index) in list" :key="item.id">
            <td>{{ index + 1 }}</td>
            <td>{{ item.subject }}</td>
            <!-- 动态样式 -->
            <td :class="{ red: item.score < 60 }">{{ item.score }}</td>
            <td>{{ dateFormat(item.date) }}</td>
            <!-- 点击事件，删除成绩 -->
            <td><a href="#" @click.prevent="deleteFn(item.id)">删除</a></td>
          </tr>
        </tbody>
        <!-- 根据数组长度显示隐藏 提示面板 和 总分平均分模块-->
        <tbody v-show="list.length===0">
          <tr>
            <td colspan="5">
              <span class="none">暂无数据</span>
            </td>
          </tr>
        </tbody>
        <tfoot v-show="list.length!==0">
          <tr>
            <td colspan="5">
              <span>总分：{{sum}}</span>
              <span style="margin-left: 50px">平均分：{{avg}}</span>
            </td>
          </tr>
        </tfoot>
      </table>
    </div>
    <div class="form">
      <div class="form-item">
        <div class="label">科目：</div>
        <div class="input">
          <input type="text" placeholder="请输入科目" v-model.trim="subject" />
        </div>
      </div>
      <div class="form-item">
        <div class="label">分数：</div>
        <div class="input">
          <input type="text" placeholder="请输入分数" v-model.number="score" />
        </div>
      </div>
      <div class="form-item">
        <div class="label"></div>
        <div class="input">
          <!-- 点击事件，添加成绩 -->
          <button class="submit" @click="addFn">添加</button>
        </div>
      </div>
    </div>
  </div>
</template>

<script>
import moment from 'moment'
export default {
  name: 'ScoreCase',
  methods: {
    //格式化时间
    dateFormat(dt) {
      return moment(dt).format('YYYY-MM-DD HH:mm:ss')
    },
    //删除成绩 filter返回元素id值不等于要删除id值的新数组
    deleteFn(id) {
      this.list = this.list.filter((item) => item.id !== id)
    },
    //添加成绩  v-model,校验,数组push,清空
    addFn() {
      if (this.subject && this.score && this.score >= 0 && this.score <= 100) {
        this.list.push({
          id: this.list.length ? this.list.at(-1).id + 1 : 1,
          subject:this.subject,
          score:this.score,
          date:new Date()
        }),
        this.subject='',
        this.score=''
      } else {
        alert('请仔细检查输入内容')
      }
    },
  },
   computed:{
    // 计算属性 总和 平均值
    sum(){
      return this.list.reduce((prev,item)=>prev + item.score,0)
    },
    avg(){
      return this.list.length? (this.sum / this.list.length).toFixed(2) : 0
    }
  },
  // 监听list 一旦数据发生改变，就更新本地存储
   watch:{
     list:{
      //因为list是数组，复杂数据类型，故要开启深度监听
      deep:true,
      handler(newVal){
        localStorage.setItem('Case-Score',JSON.stringify(newVal))

      }
    }
  },
 
  data() {
    return {
      // 从本地存储中取出list数据,若没有,则赋空数组
      list: JSON.parse(localStorage.getItem('Case-Score')) || [],
      /* [
        {
          id: 15,
          subject: '语文',
          score: 89,
          date: new Date('2022/06/07 10:00:00'),
        },
        {
          id: 27,
          subject: '数学',
          score: 100,
          date: new Date('2022/06/07 15:00:00'),
        },
        {
          id: 32,
          subject: '英语',
          score: 56,
          date: new Date('2022/06/08 10:00:00'),
        },
        {
          id: 41,
          subject: '物理',
          score: 76,
          date: new Date('2022/06/08 10:00:00'),
        },
      ], */
      subject: '',
      score: '',
    }
  },
}
</script>

<style lang="less">
.score-case {
  width: 1000px;
  margin: 50px auto;
  display: flex;
  .table {
    flex: 4;
    table {
      width: 100%;
      border-spacing: 0;
      border-top: 1px solid #ccc;
      border-left: 1px solid #ccc;
      th {
        background: #f5f5f5;
      }
      tr:hover td {
        background: #f5f5f5;
      }
      td,
      th {
        border-bottom: 1px solid #ccc;
        border-right: 1px solid #ccc;
        text-align: center;
        padding: 10px;
        &.red {
          color: red;
        }
      }
    }
    .none {
      height: 100px;
      line-height: 100px;
      color: #999;
    }
  }
  .form {
    flex: 1;
    padding: 20px;
    .form-item {
      display: flex;
      margin-bottom: 20px;
      align-items: center;
    }
    .form-item .label {
      width: 60px;
      text-align: right;
      font-size: 14px;
    }
    .form-item .input {
      flex: 1;
    }
    .form-item input,
    .form-item select {
      appearance: none;
      outline: none;
      border: 1px solid #ccc;
      width: 200px;
      height: 40px;
      box-sizing: border-box;
      padding: 10px;
      color: #666;
    }
    .form-item input::placeholder {
      color: #666;
    }
    .form-item .cancel,
    .form-item .submit {
      appearance: none;
      outline: none;
      border: 1px solid #ccc;
      border-radius: 4px;
      padding: 4px 10px;
      margin-right: 10px;
      font-size: 12px;
      background: #ccc;
    }
    .form-item .submit {
      border-color: #069;
      background: #069;
      color: #fff;
    }
  }
}
</style>